I have created a wiki page that details every unlock date (and tech removal date). Hopefully this will allow me and others to update it as updates happen. I currently believe that it is accurate but I may be wrong.
You could also include the dates leaded fuel is banned in the countries in game. (You can find that by changing the variant year for each country, from what I remember it’s around 1975-1985 for all regions.)
Not like there was a Google sheet with all that, no no Nah, joking, it was made for Kee and not updated since, so it’s not perfectly relevant anymore. Good job, I think I’ll add it to the “useful” list, many people might have not even noticed that there’s a wiki.